Method of making commutators



1964 F. scHAFER ETAL 3, 6

METHOD OF MAKING COMMUTATORS Original Filed Sept. 8, 1958 United States Patent 0 ice 3,161,947 METHOD OF MAKENG CQMMUTATGRS Fridolin ehiifer, Stuttgart, and Karl Wiel-z, Stuttgart- Rohr, Germany, asrignors to Robert Bleach @Jllhl). Stuttgart, Germany (lriginal application Sept. 8, 1958, Ser. No. 759,65 l, now Patent No. Li /a438, dated June 27, 18 61. Divided and this application Mar. M, 1961, Scr. No. 94-,8i ll Claims priority, application Germany, Get. 5, 19 57, B 46,3lltl 6 Claims. ill. i i-"15554) The present invention relates to commutators for electric machines, and more particularly to improvements in commutators of the type in which an annulus consisting of insulated dovetailed segments is held together by a pair of clamping rings and by a tubular core whose longitudinal ends are deformed or swedged to bear against the end faces of clamping rings and to thereby hold the annulus of segments in required position with respect to the axis about which the commutator revolves.

This application is a division of our copending application Serial No. 759,694, filed September 8, 1958, now Patent No. 2,990,488, entitled Commutators and Method of Making the Same.

According to the invention disclosed and claimed in a copending application of Karl Wick, Serial No. 759,695, now abandoned, displacements of dovetailed segments in commutators which comprise a rivet like core and an annularly disposed group of insulated segments is prevented by introducing a hardenable insulating substance into the space defined by the axially parallel end faces of the dovetailed portions forming part of the segments as Well as of interposed non-conducting sheets, and by the peripheral zone of the rivet like core which latter is also called the nave of a commutator. According to said invention, the insulating substance is introduced in plastic state through at least one aperture which constitutes a communicating passage between said space and the axial bore in the core of a commutator. The apparatus for introducing the hardenable insulating substance (prefer ably a material with good heat conducting characteristics, such as Bakelite, an epoxy resin, or the like) comprises a pair of rams or plungers which are introduced from opposing ends of the core into its axial bore to compress and plasticize the insulating substance therebetween, to cause flow of plastic substance through the aperture into the annular space between the dovetailed portions and the peripheral zone of the core. After hardening, the insulating substance prevents tilting of segments about the clamping rings, such tilting being undesirable because it causes rapid destruction of the runway for customary carbon brushes or wipers when the commutator is in actual use. Since the insulating substance is introduced through the axial bore of the core, its introduction must precede the mounting of a so-constructed commutatoruntothe spindle of an armature because, as is well known in ma chines of this character, the spindle also passes through the axial bore in the core or rivet of'such commutators.

An object of the present invention is to provide a novel method of filling the commutators with a hardenable insulating substance.

Another object or" the invention is to provide a commutator whose annulus of segments and of non-conducting sheets therebetween may be filled with a hardenable plasticized insulating substance after mounting of the commutator onto the spindle of an armature.

A further object of the invention is to provide a com mutator of the above described characteristics which is so constructed that the filling of its annulus with, and

coating of armature coil by, an insulating substance may Millet? Patented Dec. 22, 1964 An additional object of the invention is to provide a commutator having a rivet like core and a series of dovetailed annularly disposed segments which are so constructed that the insulating substance which prevents tilting of segments about their clamping rings may be introduced into the space surrounding the periphery of the core through a single segment or through a number of segments while the construction of all other component parts remains unchanged.

The above and other objects of the invention are at-- tained by the provision or" a commutator in which the annulus, and more particularly at least one segment defines at least one passage or channel through which the annular space between dovetailed portions and the core communicates with the surrounding atmosphere. Thus, instead of introducing the insulating material through an aperture in the core as disclosed in the aforementioned Wick application, the hardenable material may be introduced from the peripheral zone or from one or both end faces of one or more segments while the core is already mounted on the spindle of an armature and after the armature Wires are already soldered to the lugs which latter form part of wedge-shaped dovetailed segments.

The formation of communicating passages or channels in the segments may be achieved in a number of different ways. According to one embodiment of our invention, a segment is formed with at least one longitudinal cutout or groove in one or both of its major surfaces, the groove or grooves communicating with a transverse bore extending between the major surfaces or" the segment. At least one non-conducting sheet or plate adjacent to the so constructed segment or segments has its dovetailed portion formed with a cutout opening into the annular space defined by the dovetailed portions and the periphery of the commutators core. Thus, the annular space may be filled with hardenable insulating material through the groove or grooves and the transverse bore in one or more segments, and through the cutout of one or more adjacent non-conducting sheets. According to our novel method, the introduction of insulating substance is carried out in vacuo by dipping the fully assembled commutator into the hardenable substance.

According to a slight modification of the invention, at least one segment is provided with one or more bores, grooves or cutouts which may be either perpendicular or inclined with respect to the axis about which the commutator rotates, one end of each cutout terminating in an exposed surface of the segment, i.e. in its peripheral zone or in one of its end surfaces, and the other end opening into the space between the periphery of the core and the dovetailed portions of segments and of interposed non-conducting sheets.

The novel featureswhich are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of certain embodiments when read in connection with the accompanying drawing, in which:

FIG. 1 is an axial section through approximately one half of a commutator constructed in accordance with one embodiment of our invention;

FIG. 2 is a perspective view of the segment shown in FIG. 1, the segment having a pa r of longitudinal grooves and a transverse bore betweenthe grooves; j 4

FlG. 3 is a perspective view of a non-conducting sheet; FIG. 4 illustrates in perspective a modified segment having a radial groove; and

' FIG. 5 is a perspective View of a different segment having a pair of inclined grooves in its major surfaces.

Referring first to FIG. l, the commutator it comprises arenas? an annulus consisting of wedge-shaped segments 11, one of which is shown in FIG. 2, and of non-conducting sheets or plates 12 interposed between the adjacent major surfaces 'of the segments, one sheet 12 being shown in FIG. 3. Segments 11 comprise dovetailed portions 13 alternating with similar dovetailed portions 12a of non-conduct ing members 12. Dovetailed portions 13, 12a are urged in direction perpendicular to and toward the axis of a tubular core 16 by a pair of clamping rings 14-, 15 whose V-shaped extensions are received in complementary annular recesses defined by the portions 13, 12a. Rings 14, 15 extend into the axial bore of annulus constituted by members 11, 12 and are inserted into said bore from the respective' ends of the annulus. Short-circuiting of segments 11 by rings 1 15 or by core 16 is prevented by a pair of V-shaped annular insulators l8, l9 and by a cylindrical insulator 17 which latter surrounds the peripheral zone of core 16. Core 16 has a pair of deformed or swedged end portions 16a, 1611 which are bent over the end faces 'of respective clamping rings 14, 15 and urge said rings in the direction of dovetailed portions 13, 120. Core 16 constitutes the nave of commutator it) in that it receives the spindle (not shown) of an armature, and is coaxial with the annulus of segments 11 and plates 12.

In accordance with our invention, one, more or all segments 11 are formed with a pair of longitudinal cutouts or grooves 20, 21 as is best shown in FIG. 2. These grooves are provxided in the lateral or major surfaces of the segment and extend between its longitudinal end surfaces preferably so that they partially extend into the material of dovetailed portion 13. Grooves 2%, 21 are connected by a transverse bore 22 extending between the major surfaces of the segment.

Referring to FIG. 3, there is shown a non-conducting sheet or plate 12 having a dovetailed portion 12a and a cutout 23 opening into the end face 12a of portion 12a. The upper part of cutout 23 is aligned with bore 22 of an adjacent segment 11, as is shown in FIG. 1. The exposed surface of insulating insert 17 and the end faces 13, 12a on dovetailed portions 13, 12a of respective members 11, 12 define therebetween a space 24 which may be filled with a hardenable insulating substance 26 (shown broken away in FIG. 1) through grooves 21, through transverse bore 22, and through the inwardly opening cutout or aperture 23. Hence, the introduction of insulating substance 26 may be carried out after the core 16 is already mounted on the spindle of an armature. Grooves 2t 21, bore 22 and cutout 23 thus form a channel or passage for introduction of insulating material 2% and, if the commutator comprises more than one segment of construction shown in FIG. 2 and more than one-non-conducting sheet 12 of the construction shown in FIG. 3, the air from space 24 will escape through one or more channels while the material 265 is introduced through the remaining channel or channels.

It is preferred, however, to first evacuate air from space 24 and to thereupon dip the completely assembled commutator 10, after mounting same on the spindle of an armature and after the armature wires (not shown) are already soldered to lugs of individual segments 11, into a hardenable plasticized insulating substance in such mannet that the armature wires, too, are submerged into the plastic material. In this manner, the coil ends of an armature which face the commutator may be joined with the latter in a single operation to form an extremely strong unit.

The modified segment 30, shown in FIG. 4, is formed with a groove 31 extending from its exposed outer or peripheral surface 32 toward the end face 33' of its dovetailed portion 33. Thus, no cutouts or apertures need be provided in the n'on-conducting plates or sheets 12 because the hardenable insulating substance 26 may be introduced from the exposed peripheral zone of annulus constituted by segments and by interposed plates directly into the annular space 24 of the commutator. As is known, the periphery of annulus constituted by the segments and interposed non-conducting sheets is the runway for carbon brushes or Wipers (not shown) of an electric machine. It will be understood that groove 31 may be replaced by a radial or inclined bore between outer surface 32 and end face 33 of segment 30.

Referring now to FIG. 5, the segment 50 therein shown is formed with a pair of inclined grooves 51, 52 extending in its major surfaces between the opposing end surface 50a, 50b, respectively, and the longitudinal ends of end face 53' on dovetailed portion 53. If desired, the segment may be formed with a single groove 51 or 52, and such grooves may be provided in one, more or all egments of the commutator. The advantage of construction shown in FIG. 5 is in that the cutouts do not terminate in the exposed outer or peripheral surface 500 of the segment but rather in its end surfaces, so that the insulating substance filling the space 24 and the grooves or channels in the segment or segments cannot hinder the travel of wipers about the periphery of the commutator.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic andspecific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In the manufacture of commutators of the type in which the core and the annulus of dovetailed segments define therebetween an annular space which communicates with the surrounding atmosphere through a passage extending through said annulus to a point above said annular space, the steps of mounting the core on the spindle of an armature, soldering the armature wires to segments, and submerging the commutator after assembly into a hardenable plastic insulating substance for filling said space through said passage and for coating the armature wires with said substance.

2. In the manufacture of commutators of the type in which the core and the annulus of dovetailed segments define therebetween an annular space which communicates with the surrounding atmosphere through a passage extending through the annulus, the steps of mounting the core on the spindle of an armature, soldering the armature wires to segments, evacuating the an from said space through said passage, and thereupon submerging the commutator with said space in evacuated state into a hardenable plastic insulating substance for coat ng the armature wires with said substance while permitting said substance to flow through said passage into sa d space for filling the latter and said passage with said hardenable plastic insulating material.

3. In the manufacture of commutators of the type in whichthe core and the annulus of dovetailed segments definetherebetween an annular space which communicates with the surrounding atmosphere through a passage extending through said annulus to a point above said annular space, the step of submerging the commutator after assembly into a hardenable plastic insulating substance so that said space within the submerged commutator is filled by hardenable plastic entering said space from outside thereof through said passage.

4. in the manufacture of commutators of the type in which the core and the annulus of dovetailed segments define therebetween an annular space which communicat-es with the surrounding atmosphere through a passage extending through said annulus, the steps of evacuating the air from said space through said passage and of thereupon submerging the commutator, with said space in evacuated state into a hardenable plastic insulating subarenas? stance while permitting said substance to flow through said passage into said space so that said space within the submerged commutator is filled by hardenableplastic entering said space from outside thereof.

5. In the manufacture of a commutator the steps of forming a plurality of segments having each a main portion and a dovetailed portion integral with said main portion and being adapted to form an annulus with said dovetailed portions forming the inner surface of said an nulus, forming in at least one of said segments a passage providing when said segments are assembled, communication between the atmosphere and the interior of said annulus, assembling said plurality of said segments into an annulus about a hollow core by means of a pair of clamping rings having V-shaped projections extending into the cutouts formed by said dovetailed portions and insulated sheets clamped between said projections and said dovetailed portions so that an annular free space remains between the inner surface of said annulus and said core which communicates with the atmosphere only through said passage, evacuating the air from said space through said passage, and subsequently submerging the commutator with said space in evacuated state into hardenable plastic insulating substance while permitting said substance to flow through said passage into said space so that said substance will flow through said passage into said space and completely fill said space and said passage. 1

6. In the manufacture of a commutator the steps of forming a plurality of segments having each a main portion and a dovetailed portion integral with said main portion and being adapted to form an annulus with said dovetailed portions forming the inner surface of said annulus, forming in at least one of said segments a passage providing, when said segments are assembled,

communication between the atmosphere and the interior of said annulus, assembling said plurality of said segments into an annulus about a hollow core by means of a pair of clamping rings having V-shaped projections extending into the cutouts formed by said dovetailed portions and insulated sheets clamped between said projections and said dovetailed portions so that an annular free space remains between the inner surface of said annulus and said core which communicates with the atmosphere through only said passage, mounting the core on the spindle or" an armature, soldering the armature wires to segments, evacuating air through said passage from said annular space, and submerging the commutator with said annular space in evacuated state subsequently into a hardenable plastic insulating substance while permitting said substance to flow through said passage into said space for filling said space through said passage and for coating the armature wires with said substance.

References tilted by the Examiner UNITED STATES PATENTS 1,325,325 12/19 Janke 29-15554 1,354,005 9/20 Sloan 18-59 1,707,596 4/29 Bertram 29-15554 1,883,736 10/32 Cotterman 29-15554 2,477,273 7/49 Tognola 1859 2,671,866 3/54 Carnprubi 29-15554 2,795,841 6/57 Eppich 29-15554 2,920,378 1/60 Nichols et a1 29-15554 2,941,905 6/69 Both-nan 18-59 JOHN F. CAMPBELL, Primary Examiner.

WHETMQRE A. WELTZ, Examiner. 

1. IN THE MANUFACTURE OF COMMUTATORS OF THE TYPE IN WHICH THE CORE AND THE ANNULUS OF DOVETAILED SEGMENTS DEFINE THEREBETWEEN AN ANNULAR SPACE WHICH COMMUNICATES WITH THE SURROUNDING ATMOSPHERE THROUGH A PASSAGE EXTENDING THROUGH SAID ANNULUS TO A POINT ABOVE SAID ANNULAR SPACE, THE STEPS OF MOUNTING THE CORE ON THE SPINDLE OF AN ARMATURE, SOLDERING THE ARMATURE WIRES TO SEGMENTS, AND SUBMERGING THE COMMUTATOR AFTER ASSEMBLY INTO A HARDENABLE PLASTIC INSULATING SUBSTANCE FOR FILLING SAID SPACE THROUGH SAID PASSAGE AND FOR COATING THE ARMATURE WIRES WITH SAID SUBSTANCE. 